Check out Tk Realtime data aquisition . It could be improved quite easily, like having the y axis float along with the leading edge, and you could setup a timer to snap a photo and regular intervals.
I'd go for rrdtool. oss.oetiker.ch/rrdtool/
there are perl bindings availale for it, or you can call it using 'system'.
Monitors a hole lotta webservers for me.